I want to share my related code and photo here. The program runs on an STM32F746 Nucleo Board. It uses timer 2 to trigger DMA1 stream 0 causing fixed-length transmission of data via SPI 1 to an external ADC without interrupts on the transmission side. Timer 2 confüguration is settled at 25600Hz this is used as a sample rate. Therefore data must be received with SPI3 every 25600Hz. I created a test pin to understand that the sampling process is finished. The sample size is 64. The complete time is 64 x 1/25600 = 400Hz. I can see this period with diligent oscilloscope but the received data is empty. Can you show me where I'm doing wrong?
Code:
SPI_HandleTypeDef hspi3;
DMA_HandleTypeDef hdma_spi3_rx;
TIM_HandleTypeDef htim2;
DMA_HandleTypeDef hdma_tim2_up_ch4;
#define fs (25600)
#define RX_BUFFER_LENGTH (64)
memset(rxBuffer, 0, sizeof(rxBuffer));
txBuffer = 0xFFFF;
// Start SPI RX DMA
hspi3.hdmarx->XferCpltCallback = mySPI_DMAReceiveCplt;
SET_BIT(hspi3.Instance->CR2, SPI_RXFIFO_THRESHOLD);
HAL_GPIO_WritePin(ADC_CS_Pin_GPIO_Port, ADC_CS_Pin_Pin, RESET);
HAL_DMA_Start_IT(hspi3.hdmarx, (uint32_t)&hspi3.Instance->DR, (uint32_t)rxBuffer, RX_BUFFER_LENGTH);
SET_BIT(hspi3.Instance->CR2, SPI_CR2_RXDMAEN);
__HAL_SPI_ENABLE(&hspi3);
// Prepare TIM DMA to SPI_DR
HAL_DMA_Start(htim2.hdma[TIM_DMA_ID_UPDATE], (uint32_t)&txBuffer, (uint32_t)&hspi3.Instance->DR, 1);
__HAL_TIM_ENABLE_DMA(&htim2, TIM_DMA_UPDATE);
// Start the timer
__HAL_TIM_ENABLE(&htim2);
while (1)
{
}
static void mySPI_DMAReceiveCplt(DMA_HandleTypeDef *hdma)
{
if( hdma == &hdma_spi3_rx )
{
HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_6); // IO test pin
}
}
